Section 1018 addresses guards (railings protecting open edges), handrails (graspable supports), and balustrades (infill panels below railings). Guard height must be minimum 42 inches above floor or adjacent walking surface, measured vertically. Guards on stairs are measured at the nosing of the stair. Baluster spacing must not permit passage of 4-inch diameter ball to prevent child entrapment. Openings or geometric patterns in the guard must not permit passage of 6-inch diameter ball. Horizontal members such as bottom rails are permitted to be spaced up to 36 inches apart. Handrails must be graspable with diameter 1.25-2 inches, permitting full-hand grasping. Non-circular handrails with flat edges or elongated shapes are permitted if they meet geometric requirements. Handrails must be mounted 34-38 inches above stair nosing or walking surface. Extensions are required at top and bottom of stairs, typically 12 inches beyond the first and last stairs. Handrail continuity is required at stair direction changes. Starting platforms (landings) must not drop below handrail end. Doors at stairwell entrances may be acceptable instead of handrail extensions where space is limited. Residential handrails may be smaller diameter (1.25-1.5 inches) compared to public building handrails.